Merck Warned Europe That Propecia Causes Sexual Problems -- but Not the U.S.

By Jim Edwards

Updated on: March 22, 2011 / 9:50 AM
/ MoneyWatch

Merck (MRK) has some explaining to do about why its warnings of the risk of persistent or permanent sexual dysfunction in men taking the hair loss drug Propecia are different depending on where you live and how much you take.

In addition, Merck's warning for the prostate drug Proscar -- which is the same chemical as Propecia, finasteride, except at a higher dose -- also warns of "prolonged adverse effects on sexual function such as erectile dysfunction and diminished libido."

For men with male pattern hair loss, Propecia remains an important treatment option for appropriate patients. Merck encourages healthcare providers and consumers to report any adverse experience associated with any Merck medication or vaccine. Patients should talk with their healthcare providers if they have any questions about the benefits and risks of Propecia.

As Nalty notes, there is a good reason why Propecia might damage sexual function: finasteride inhibits the enzyme that converts testosterone into dihydrotestosterone (DHT). DHT causes baldness. Unfortunately, DHT is also what men need to keep their mojo working.